1. FIELD OF THE INVENTION
The present invention pertains generally to the field of walking aids for invalids and is more particularly directed to improved double bow crutch constructions provided with a stair deflector.
2. STATE OF THE PRIOR ART
Double axillary crutches typically comprise two parallel members connected at their upper end by an armrest adapted to fit against a patient's armpit, and bowed inwardly towards each other at their lower ends. An adjustable footpiece is mounted between the two bow members and extends downwardly from the lower curved ends of the bow members to terminate in a tip which makes contact with the ground surface. The footpiece may be a single straight member which is slidable between the two bow members such that it may be fixed at any convenient position, thereby setting a desired overall crutch length. In other crutch designs the foot piece includes two or more telescoping sections, the uppermost of which is fixed between the two bow members while one or more lower sections can be telescoped and fixed at a convenient extension length so as to set the crutch height.
A frequent problem encountered in this type of double bow crutch constructions has been that the lower ends of the bow members terminate in squared-off transverse surfaces adjacent to the footpiece. These transverse surfaces may be quite close to the ground depending on the extension setting of the foot piece and are capable of catching against stair edges when a patient is ascending or descending a staircase. This has led in the past to accidents and injuries.
This applicant is aware of existing crutch configurations which incorporate means for protecting against such accidental engagement of the crutch with the stair edges by providing stair deflector edges or surfaces at the lower ends of the bow members. These are slanting surfaces which cause the crutch to deflect away from and prevent false engagement with stair edges unless the bottom tip of the crutch is firmly set on a horizontal supporting surface. The provision of the slanting stair deflecting edges or surfaces deprive the stair edge from the transverse end surface on which to catch at the lower ends of the two bow members. Such crutch constructions are disclosed by Arndt in U.S. Pat. No. 1,505,081 and to at least some extent by Walton, U.S. Pat. No. 1,035,760.
The Arndt patent is directed to a crutch which has a one piece nontelescoping footpiece. Walton does address the problem of providing stair deflector means in a crutch with a telescoping foot piece, which however does not provide a completely satisfactory solution. The Walton footpiece is illustrated as comprising three telescoping segments. The uppermost segment is fixed in position between the two bow members while the intermediate segment can be telescoped into the upper fixed segment. The lower ends of the bow members are fitted with a cap which provides tapering lateral edges or surfaces which are capable of deflecting staircase edges. However, the sole means of interlocking the fixed and intermediate footpiece segments so as to lock the footpiece is a single screw threaded through the end cap. Provision of a single point of support of the telescoping intermediate footpiece segment is inadequate to prevent wobble of the intermediate segment within the upper fixed segment of the footpiece since a certain amount of clearance is required between the two segments to allow easy sliding.